1. Field of the Invention
The invention relates to an inverter and a drive system using the inverter.
2. Description of the Related Art
Introduction of electric vehicles (EV), hybrid electric vehicles (HEV), and fuel cell vehicles (FCV) has been actively pursued in recent years due to heightening concerns over environmental problems. In the meanwhile, various types of rechargeable batteries are being developed as the source of electric power for the motors used on these vehicles.
The DC provided by a typical rechargeable battery, i.e., motor-driving battery, is seldom supplied to a motor directly, but rather is changed to AC and its voltage is often raised to a higher voltage before it is delivered to an AC motor to drive it. An inverter is used to change the DC from a rechargeable battery to AC.
The inverter of related art changes the DC from a rechargeable battery to AC typically by chopping the DC with a switching device. Typical inverters of prior art such as those disclosed by the Unexamined Patent Publications 2003-009541 and 2003-255012 use devices such as smoothing capacitors in order to suppress ripple currents that develop during the process of changing DC to AC.